Photoacclimation in freshwater diatoms: interspecific and inter-habitat comparisons

Abstract

Diatoms are a type of photosynthetic phytoplankton that can acclimate to the light level of their environment. Diatoms from different habitats exhibit different photoacclimation characteristics; those from relatively low-light intensity habitats present relatively high photosynthetic activity, high light-harvesting pigment (Chla) content, and low xanthophyll content. Conversely, diatoms from high-light intensity environments have lower photosynthetic activity, less Chla content, and efficient xanthophyll cycling. Hence, diatoms can maintain high growth and photosynthetic activity within a wide range of light intensities. Whether the mechanisms of such adaptability are a consequence of biological photoacclimation to different light intensities or interspecific differences is unknown. Here, we show that differences in photoacclimation ability are more significant than species differences. We found similar species compositions in low- and high-light habitats of the Hanjiang River, China; however, there were remarkable differences in rapid light-response curve parameters. The photoacclimation of algae and trends in their photosynthetic activity can be estimated by rapid detection techniques. We isolated three diatom species common to both habitats and grew them under various light intensities, finding that they have an excellent ability to acclimate to local light conditions. Diatoms can use physiological strategies to handle light fluctuations, but only for short periods. Our results provide a theoretical basis for controlling algal blooms through light management. With knowledge of the photoacclimation characteristics of diatoms and according to the availability of local water conservancy facilities, it is possible to use light management to control diatom blooms more efficiently than with conventional techniques, thereby reducing water usage.